It is a very important technology to specify a position of an object being located on the ground and having been shot from the air on a map, in view of facilitating judgment of situations on the ground in the case of occurrence of any natural disaster such as earthquake, fire or any man-made disaster such as explosion, serious accident. In the conventional positional specification method and device, as shown, for example, in the Japanese Patent No. 2695393, a shooting position in the air is specified three-dimensionally, a direction of a target with respect to a shooting position is measured, a ground surface where the target resides is obtained based on a three-dimensional topographic data including altitude information as to undulation of the ground surface which data has been preliminarily prepared, and a position of the target on the ground surface having been shot from the air is specified as a point of intersection of the ground surface with a straight line extending from the shooting position toward the target.
In the conventional positional specification method and device, to specify the position of a target on the ground surface, a three-dimensional topographic data including altitude information as to undulation of the ground surface which data has been preliminarily prepared is needed as a prerequisite. Further, measurement error that occurs at the time of specifying three-dimensionally a shooting position in the air and at the time of measuring the direction of a target with respect to the shooing position cannot be compensated, thus making it hard to specify a position with accuracy. Furthermore, since the positional specification is executed with respect to one point of target, a problem exists in that situations on the ground surface cannot be understood area-wide.